It has to hang, not be pinned
A vinyl panel expands and contracts along its length with temperature — measurably, every day. It is designed to hang on the nail rather than be clamped by it, so the fastener sits slightly proud and the panel slides behind the head.
Nail it home and the panel has nowhere to go. It buckles in the first hot week and stays buckled, because the distortion is permanent. Wavy vinyl on a wall is almost never a bad product; it is a crew that drove the nails tight.
The wall behind it does the work
Vinyl is a rain screen, not a seal. Water is expected to get behind it and expected to drain back out, which makes the weather-resistant barrier, the flashing and the condition of the sheathing more important than which panel you chose.
It is also why we take the old siding off instead of going over it. Going over hides whatever is rotting underneath and creates a second cavity for water to sit in, and it makes the next repair worse than it needed to be.
Insulated vinyl, and when it is worth buying
Insulated panels have foam bonded to the back. They are noticeably more rigid, which makes the wall look flatter and sound less hollow, and they resist denting better than hollow-back panels.
The honest version: buy it for the rigidity and the flatness. The added insulation is real but modest, and if somebody is selling insulated vinyl mainly on what it will do to your heating bill, ask them to put the figure in writing.
Colour, fade and the matching problem
Darker colours absorb more heat and shift sooner, and a south or west elevation ages ahead of the rest of the house regardless of colour. Modern formulations hold far better than they used to, but the sunny wall still shows age first.
Matching matters later rather than now. Profiles and colours get discontinued, so a partial repair on a wall that is ten years old often cannot be matched exactly. We will tell you when a patch is going to be visible instead of fitting it and letting you notice.